1. Field of the Invention
The present invention relates to the preparation of straight chain aldehydes. More particularly, the invention relates to the preparation of straight chain aldehydes by an amine-modified oxo process.
2. Description of the Prior Art
The preparation of aldehydes by the hydroformylation of olefins, also called the oxo process, is generally known. See, for instance, the chapter on "Oxo Process" in Kirk-Othmer Encyclopedia of Chemical Technology, 2nd Ed., published 1963, in Volume 14, page 373.
The production of straight chain aldehydes from straight chain olefins by the hydroformylation reaction is particularly desirable because of the generally superior performance of products derived therefrom. For example, the aldehydes are readily oxidized to carboxylic acids which by their linearity are useful in the production of synthetic ester lubricants. Also, the aldehydes undergo aldol condensation to give higher aldehydes useful for production of higher alcohols. The straight chain alcohols obtained by hydrogenation of straight chain aldehydes are sulfated to provide superior alkyl sulfate detergents.
It has been suggested that straight chain products may be obtained by the hydroformylation reaction when the usual cobalt catalyst is modified with phosphines, perferably trialkyl or alicyclic phosphines. See, for instance, U.S. Pat. No. 3,239,569.
It has also been suggested that straight chain products may be obtained by the hydroformylation reaction with 1-alkenes with conventional cobalt catalysts at particular temperatures in the range of 60.degree. to 100.degree. C. The reaction is extremely slow below 100.degree. C. See, for instance, U.S. Pat. No. 2,824,344.
The use of weak amines to accelerate the hydroformylation reaction has been suggested, but no effect on the straight chain content was observed. See, for instance, U.S. Pat. No. 2,820,059.
Polyamines such as ethylene diamine have been employed in the preparation of transition metal complexes of unknown nature for catalysts in hydroformylation. See, for instance, U.S. Pat. No. 3,594,425.
Substituted pyridines have been suggested to accelerate the oxo reaction but in general it was found that product linearity was greatly reduced. See, for instance, U.S. Pat. No. 3,231,621.